Overhead doors are widely employed as garage closures because they achieve the desired result with minimal loss of floor space. It is desired to construct such doors from relatively lightweight materials such as fiberglass and sheet metal panels to reduce the difficulty involved in raising and lowering the door. However, even relatively light weight doors can weigh in excess of three hundred pounds.
A particular problem with large area doors arises in geographic areas such as so-called "hurricane zones" which are subject to high wind conditions. The wind load on a double width garage door can cause the door to flex inwardly at the center and sufficient flexing can cause permanent deformation and, at the extreme, catastrophic failure.
Various constructions have been proposed to address the need for reinforcement in sectional garage and warehouse doors. Examples of such reinforcing constructions are shown, for example, in U.S. Pat. No. 3,443,625 "Reinforced Collapsible Door", issued May 13, 1969 to Moser et al. and U.S. Pat. No. 5,445,207, "Reinforced Collapsible Garage Door Assembly," issued Aug. 29, 1995 to Romanelli et al. as well as in U.S. Pat. No. 4,974,058 "Sheet Shutter" issued Dec. 4, 1990 to Komatsu et al and which discloses a roll-up warehouse door. Although the latter patent proposes the use of pipes as reinforcement members, reinforcement of a garage door is more typically achieved through the addition of long horizontal interior struts which are roll shaped into a hollow, rectangular beam shape and attached to the interior, vertical door stiles by sheet metal screws. These struts generally exhibit small radius corners which act as stress concentrators. Moreover, they are commonly used in multiples per door panel and can add considerably to the overall weight of the door.